From prevention to diagnosis and treatment: Biomedical applications of metal nanoparticle-hydrogel composites

Hydrogel-Based Systems in Neuro-Vascularized Bone Regeneration: A Promising Therapeutic Strategy

Blood vessels and nerve fibers are distributed throughout the skeletal tissue, which enhance the development and function of each other and have an irreplaceable role in bone formation and remodeling. Despite significant progress in bone tissue engineering, the inadequacy of nerve-vascular network reconstruction remains a major limitation. This is partly due to the difficulty of integrating and regulating multiple tissue types with artificial materials. Thus, understanding the anatomy and underlying coupling mechanisms of blood vessels and nerve fibers within bone to further develop neuro-vascularized bone implant biomaterials is an extremely critical aspect in the field of bone regeneration. Hydrogels have good biocompatibility, controllable mechanical characteristics, and osteoconductive and osteoinductive properties, making them important candidates for research related to neuro-vascularized bone regeneration. This review reports the classification and physicochemical properties of hydrogels, with a focus on the application advantages and status of hydrogels for bone regeneration. The authors also highlight the effect of neurovascular coupling on bone repair and regeneration and the necessity of achieving neuro-vascularized bone regeneration. Finally, the recent progress and design strategies of hydrogel-based biomaterials for neuro-vascularized bone regeneration are discussed.

Nanoparticles incorporated hydrogels for delivery of antimicrobial agents: developments and trends

The prevention and treatment of microbial infections is an imminent global public health concern due to the poor antimicrobial performance of the existing antimicrobial regime and rapidly emerging antibiotic resistance in pathogenic microbes. In order to overcome these problems and effectively control bacterial infections, various new treatment modalities have been identified. To attempt this, various micro- and macro-molecular antimicrobial agents that function by microbial membrane disruption have been developed with improved antimicrobial activity and lesser resistance. Antimicrobial nanoparticle-hydrogels systems comprising antimicrobial agents (antibiotics, biological extracts, and antimicrobial peptides) loaded nanoparticles or antimicrobial nanoparticles (metal or metal oxide) constitute an important class of biomaterials for the prevention and treatment of infections. Hydrogels that incorporate nanoparticles can offer an effective strategy for delivering antimicrobial agents (or nanoparticles) in a controlled, sustained, and targeted manner. In this review, we have described an overview of recent advancements in nanoparticle-hydrogel hybrid systems for antimicrobial agent delivery. Firstly, we have provided an overview of the nanoparticle hydrogel system and discussed various advantages of these systems in biomedical and pharmaceutical applications. Thereafter, different hybrid hydrogel systems encapsulating antibacterial metal/metal oxide nanoparticles, polymeric nanoparticles, antibiotics, biological extracts, and antimicrobial peptides for controlling infections have been reviewed in detail. Finally, the challenges and future prospects of nanoparticle-hydrogel systems have been discussed.

Antimicrobial activity of metal-based nanoparticles: a mini-review

The resistance of pathogenic microorganisms to antibiotics is one of the main problems of world health. Of particular concern are multidrug-resistant (MDR) bacteria. Infections caused by these microorganisms affect the appearance of acute or chronic diseases. In this regard, modern technologies, such as nanomaterials (NMs), especially promising nanoparticles (NPs), can possess antimicrobial properties or improve the effectiveness and delivery of known antibiotics. Their diversity and characteristics, combined with surface functionalization, enable multivalent interactions with microbial biomolecules. This article presents an overview of the most current research on replacing antibiotics with NPs, including the prospects and risks involved.

Repair of Infected Bone Defects with Hydrogel Materials

Infected bone defects represent a common clinical condition involving bone tissue, often necessitating surgical intervention and antibiotic therapy. However, conventional treatment methods face obstacles such as antibiotic resistance and susceptibility to postoperative infections. Hydrogels show great potential for application in the field of tissue engineering due to their advantageous biocompatibility, unique mechanical properties, exceptional processability, and degradability. Recent interest has surged in employing hydrogels as a novel therapeutic intervention for infected bone repair. This article aims to comprehensively review the existing literature on the anti-microbial and osteogenic approaches utilized by hydrogels in repairing infected bones, encompassing their fabrication techniques, biocompatibility, antimicrobial efficacy, and biological activities. Additionally, the potential opportunities and obstacles in their practical implementation will be explored. Lastly, the limitations presently encountered and the prospective avenues for further investigation in the realm of hydrogel materials for the management of infected bone defects will be deliberated. This review provides a theoretical foundation and advanced design strategies for the application of hydrogel materials in the treatment of infected bone defects.

One-Pot Synthesis of a Robust Crosslinker-Free Thermo-Reversible Conducting Hydrogel Electrode for Epidermal Electronics

Traditional epidermal electrodes, typically made of silver/silver chloride (Ag/AgCl), have been widely used in various applications, including electrophysiological recordings and biosignal monitoring. However, they present limitations due to inherent material mismatches with the skin. This often results in high interface impedance, discomfort, and potential skin irritation, particularly during prolonged use or for individuals with sensitive skin. While various tissue-mimicking materials have been explored, their mechanical advantages often come at the expense of conductivity, resulting in low-quality recordings. We herein report the facile fabrication of conducting and stretchable hydrogels using a "one-pot" method. This approach involves the synthesis of a natural hydrogel, termed Golde, composed of abundant and eco-friendly components, including gelatin, chitosan, and glycerol. To enhance the conductivity of the hydrogel, various conducting materials, such as poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS), thermally reduced graphene (TRG), and MXene, are introduced. The resulting conducting hydrogels exhibit remarkable robustness, do not require crosslinkers, and possess a unique thermo-reversible property, simplifying the fabrication process and ensuring enhanced long-term stability. Moreover, their fabrication is sustainable, as it employs environmentally friendly materials and processes while retaining their skin-friendly characteristics. The resulting hydrogel electrodes were tested for electrocardiogram (ECG) signal acquisition and outperformed commercial electrodes even when implemented in an all-flexible electrode setup simply using copper tape, owing to their inherent adhesiveness.

Self-healing hydrogels based on biological macromolecules in wound healing: A review

The complete healing of skin wounds has been a challenge in clinical treatment. Self-healing hydrogels are special hydrogels formed by distinctive physicochemically reversible bonds, and they are considered promising biomaterials in the biomedical field owing to their inherently good drug-carrying capacity as well as self-healing and repair abilities. Moreover, natural polymeric materials have received considerable attention in skin tissue engineering owing to their low cytotoxicity, low immunogenicity, and excellent biodegradation rates. In this paper, we review recent advances in the design of self-healing hydrogels based on natural polymers for skin-wound healing applications. First, we outline a variety of natural polymers that can be used to construct self-healing hydrogel systems and highlight the advantages and disadvantages of different natural polymers. We then describe the principle of self-healing hydrogels in terms of two different crosslinking mechanisms-physical and chemical-and dissect their performance characteristics based on the practical needs of skin-trauma applications. Next, we outline the biological mechanisms involved in the healing of skin wounds and describe the current application strategies for self-healing hydrogels based on these mechanisms. Finally, we analyze and summarize the challenges and prospects of natural-material-based self-healing hydrogels for skin applications.

Fabrication and Actuation of Magnetic Shape-Memory Materials

Soft actuators are deformable materials that change their dimensions or shape in response to external stimuli. Among the various stimuli, remote magnetic fields are one of the most attractive forms of actuation, due to their ease of use, fast response, and safety in biological systems. Composites of magnetic particles with polymer matrices are the most common materials for magnetic soft actuators. In this paper, we demonstrate the fabrication and actuation of magnetic shape-memory materials based on hydrogels containing field-structured magnetic particles. These actuators are formed by placing the pregel dispersion into a mold of the desired on-field shape and exposing it to a homogeneous magnetic field until the gel point is reached. At this point, the material may be removed from the mold and fully gelled in the desired off-field shape. The resultant magnetic shape-memory material then transitions between these two shapes when it is subjected to successive cycles of a homogeneous magnetic field, acting as a large deformation actuator. For actuators that are planar in the off-field state, this can result in significant bending to return to the on-field state. In addition, it is possible to make shape-memory materials that twist under the application of a magnetic field. For these torsional actuators, both experimental and theoretical results are given.

Meeting Contemporary Challenges: Development of Nanomaterials for Veterinary Medicine

In recent decades, nanotechnology has been rapidly advancing in various fields of human activity, including veterinary medicine. The review presents up-to-date information on recent advancements in nanotechnology in the field and an overview of the types of nanoparticles used in veterinary medicine and animal husbandry, their characteristics, and their areas of application. Currently, a wide range of nanomaterials has been implemented into veterinary practice, including pharmaceuticals, diagnostic devices, feed additives, and vaccines. The application of nanoformulations gave rise to innovative strategies in the treatment of animal diseases. For example, antibiotics delivered on nanoplatforms demonstrated higher efficacy and lower toxicity and dosage requirements when compared to conventional pharmaceuticals, providing a possibility to solve antibiotic resistance issues. Nanoparticle-based drugs showed promising results in the treatment of animal parasitoses and neoplastic diseases. However, the latter area is currently more developed in human medicine. Owing to the size compatibility, nanomaterials have been applied as gene delivery vectors in veterinary gene therapy. Veterinary medicine is at the forefront of the development of innovative nanovaccines inducing both humoral and cellular immune responses. The paper provides a brief overview of current topics in nanomaterial safety, potential risks associated with the use of nanomaterials, and relevant regulatory aspects.

Fabrication and Validation of a 3D Portable PEGDA Microfluidic Chip for Visual Colorimetric Detection of Captured Breast Cancer Cells

To guide therapeutic strategies and to monitor the state changes in the disease, a low-cost, portable, and easily fabricated microfluidic-chip-integrated three-dimensional (3D) microchamber was designed for capturing and analyzing breast cancer cells. Optimally, a colorimetric sensor array was integrated into a microfluidic chip to discriminate the metabolites of the cells. The ultraviolet polymerization characteristic of poly(ethylene glycol) diacrylate (PEGDA) hydrogel was utilized to rapidly fabricate a three-layer hydrogel microfluidic chip with the designed structure under noninvasive 365 nm laser irradiation. 2-Hydroxyethyl methacrylate (HEMA) was added to the prepolymer in order to increase the adhesive capacity of the microchip's surface for capturing cells. 1-Vinyl-2-pyrrolidone (NVP) was designed to improve the toughness and reduce the swelling capacity of the hydrogel composite. A non-toxic 3D hydrogel microarray chip (60 mm × 20 mm × 3 mm) with low immunogenicity and high hydrophilicity was created to simulate the real physiological microenvironment of breast tissue. The crisscross channels were designed to ensure homogeneous seeding density. This hydrogel material displayed excellent biocompatibility and tunable physical properties compared with traditional microfluidic chip materials and can be directly processed to obtain the most desirable microstructure. The feasibility of using a PEGDA hydrogel microfluidic chip for the real-time online detection of breast cancer cells' metabolism was confirmed using a specifically designed colorimetric sensor array with 16 kinds of porphyrin, porphyrin derivatives, and indicator dyes. The results of the principal component analysis (PCA), the hierarchical cluster analysis (HCA), and the linear discriminant analysis (LDA) suggest that the metabolic liquids of different breast cells can be easily distinguished with the developed PEGDA hydrogel microfluidic chip. The PEGDA hydrogel microfluidic chip has potential practicable applicability in distinguishing normal and cancerous breast cells.

Nano-sized warriors: zinc chromium vanadate nanoparticles as a dual solution for eradicating waterborne enterobacteriaceae and fighting cancer

The revolution of biomedical applications has opened new avenues for nanotechnology. Zinc Chromium vanadate nanoparticles (VCrZnO4 NPs) have emerged as an up-and-coming candidate, with their exceptional physical and chemical properties setting them apart. In this study, a one-pot solvothermal method was employed to synthesize VCrZnO4 NPs, followed by a comprehensive structural and morphological analysis using a variety of techniques, including X-Ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Energy-dispersive X-ray, and X-ray photoelectron spectroscopy. These techniques confirmed the crystallinity of the NPs. The VCrZnO4 NPs were tested for their antibacterial activity against primary contaminants such as Enterobacteriaceae, including Shigella flexneri, Salmonella cholerasis, and Escherichia coli, commonly found in hospital settings, using the broth dilution technique. The results indicated a stronger antibacterial activity of VCrZnO4 NPs against Shigella and Salmonella than E. coli. Electron microscopy showed that the NPs caused severe damage to the bacterial cell wall and membrane, leading to cell death. In addition, the study evaluated the anticancer activities of the metal complexes in vitro using colorectal cancer cells (HCT-116) and cervical cancer cells (HELA), along with non-cancer cells and human embryonic kidney cells (HEK-293). A vanadium complex demonstrated efficient anticancer effects with half-inhibitory concentrations (IC₅₀) of 38.50+3.50 g/mL for HCT-116 cells and 42.25+4.15 g/mL for HELA cells. This study highlights the potential of Zinc Chromium vanadate nanoparticles as promising candidates for antibacterial and anticancer applications. Various advanced characterization techniques were used to analyze the properties of nanomaterials, which may help develop more effective and safer antibacterial and anticancer agents in the future.

Plasma-Activated Hydrogels for Microbial Disinfection

A continuous risk from microbial infections poses a major environmental and public health challenge. As an emerging strategy for inhibiting bacterial infections, plasma-activated water (PAW) has proved to be highly effective, environmental-friendly, and non-drug resistant to a broad range of microorganisms. However, the relatively short lifetime of reactive oxygen and nitrogen species (RONS) and the high spreadability of liquid PAW inevitably limit its real-life applications. In this study, plasma-activated hydrogel (PAH) is developed to act as reactive species carrier that allow good storage and controlled slow-release of RONS to achieve long-term antibacterial effects. Three hydrogel materials, including hydroxyethyl cellulose (HEC), carbomer 940 (Carbomer), and acryloyldimethylammonium taurate/VP copolymer (AVC) are selected, and their antibacterial performances under different plasma activation conditions are investigated. It is shown that the composition of the gels plays the key role in determining their biochemical functions after the plasma activation. The antimicrobial performance of AVC is much better than that of PAW and the other two hydrogels, along with the excellent stability to maintain the antimicrobial activity for more than 14 days. The revealed mechanism of the antibacterial ability of the PAH identifies the unique combination of short-lived species (¹ O₂ , ∙OH, ONOO^- and O₂ ^- ) stored in hydrogels. Overall, this study demonstrates the efficacy and reveals the mechanisms of the PAH as an effective and long-term disinfectant capable of delivering and preserving antibacterial chemistries for biomedical applications.

Calcium phosphate bone cements as local drug delivery systems for bone cancer treatment

Bone cancer is usually a metastatic disease, affecting people of all ages. Its effective therapy requires a targeted drug administration locally at the cancer site so that the surrounding healthy organs and tissues stay unharmed. Upon a thorough literature search, a tremendous number of published articles are reporting on development of calcium phosphate cements (CPCs) for the treatment of a variety of diseases, such as osteoporosis, osteoarthritis, osteomyelitis, and other musculoskeletal disorders. However, just a limited number of research employs CPCs specifically for bone cancer treatment. In this review article, we study the factors influencing the local drug release from CPCs and particularly focus on bone cancer therapy. Finally, we locate the deficiencies in the literature regarding this specific topic and propose which other perspectives should be considered and discussed in future articles.

Demystifying the Chemical Ordering of Multimetallic Nanoparticles

ConspectusMultimetallic nanoparticles (NPs) have highly tunable properties due to the synergy between the different metals and the wide variety of NP structural parameters such as size, shape, composition, and chemical ordering. The major problem with studying multimetallic NPs is that as the number of different metals increases, the number of possible chemical orderings (placements of different metals) for a NP of fixed size explodes. Thus, it becomes infeasible to explore NP energetic differences with highly accurate computational methods, such as density functional theory (DFT), which has a high computational cost and is typically applied to up to a couple of hundred metal atoms. Here, we demonstrate a methodology advancing NP simulations by effectively exploring the vast materials space of multimetallic NPs and accurately identifying the ones with the most thermodynamically preferred chemical orderings. With accuracies reaching that of DFT, our methodology is applicable to practically any NP size, shape, and metal composition. We achieve this by significantly advancing the bond-centric (BC) model, a physics-based model that has been previously shown to rapidly predict bimetallic NP cohesive energies (CEs). Specifically, the BC model is trained in a way to understand how the bimetallic bond strength changes under different coordination environments present on a NP and how the metal composition of every site affects the detailed coordination environment using fractional coordination numbers. This newly modified BC model leads to an improvement from 0.331 (original model) to 0.089 eV/atom in CE predictions when compared to DFT values on a robust data set of 90 different NPs consisting of PtPd, AuPt, and AuPd NPs with varying compositions and chemical orderings. By incorporating the modified BC model into an in-house-developed genetic algorithm (GA) we can effectively and accurately predict the most stable chemical orderings of large, realistic bimetallic NPs consisting of thousands of metal atoms. This is demonstrated on AuPd bimetallic NPs, a challenging system due to the similarity in the cohesion of the two metals. By training our BC model using a unique DFT calculation on a bimetallic NP (one calculation for two metals combining together), we expand to explore the chemical ordering of multimetallic NPs. We first demonstrate the application of our methodology on a AuPdPt NP and validate our stability predictions with literature data. Then, we effectively explore the vast materials space of multimetallic NPs consisting of combinations of Au, Pt, and Pd as a function of metal composition. Our thermodynamic stability trends are presented in a ternary diagram revealing detailed, and yet, unexpected chemical ordering trends. Our computational framework can aid both experimental and computational researchers toward effectively screening multimetallic NP stability. Moreover, we provide an outlook of how this framework can be applied to catalyst discovery, high-entropy alloys, and single-atom alloys.

Different Curcumin-Loaded Delivery Systems for Wound Healing Applications: A Comprehensive Review

Curcumin or turmeric is the active constituent of Curcuma longa L. It has marvelous medicinal applications in many diseases. When the skin integrity is compromised due to either acute or chronic wounds, the body initiates several steps leading to tissue healing and skin barrier function restoration. Curcumin has very strong antibacterial and antifungal activities with powerful wound healing ability owing to its antioxidant activity. Nevertheless, its poor oral bioavailability, low water solubility and rapid metabolism limit its medical use. Tailoring suitable drug delivery systems for carrying curcumin improves its pharmaceutical and pharmacological effects. This review summarizes the most recent reported curcumin-loaded delivery systems for wound healing purposes, chiefly hydrogels, films, wafers, and sponges. In addition, curcumin nanoformulations such as nanohydrogels, nanoparticles and nanofibers are also presented, which offer better solubility, bioavailability, and sustained release to augment curcumin wound healing effects through stimulating the different healing phases by the aid of the small carrier.

Synthesis of poly (N-isopropyl acrylamide-co-2-acrylamido methylpropane sulfonic acid) hydrogel containing copper and nickel nanoparticles with easy recycling and efficient catalytic potential

Poly(N-isopropyl acrylamide-co-2-acrylamido methyl propane sulfonic acid) hydrogel was prepared and used as matrix for the fabrication of nickel and copper nanoparticles. Nickel and copper nanoparticles were fabricated via in situ reduction of Ni (II) and Cu (II) ions within the hydrogel matrix. The manufactured hydrogel and its corresponding composites with Ni and Cu nanoparticles were characterized by FTIR, XRD, EDX, TEM, and TGA. Thermal stability of hydrogel was found to be increased upon fabricating with metal nanoparticles. The hydrogel showed ability to absorb water 63 times of its weight in dried form. The Ni and Cu nanoparticles were observed to be well dispersed, spherical in shape and most of them were having diameters in the range of 12.5 to 38.8 nm and 58 to 102 nm, respectively. The as-prepared hydrogel-nickel and hydrogel-Cu nanocomposite were used as catalysts for the reduction of a toxic pollutant 4-nitrophenol. At 25 °C, the reduction of 4-NP was found to proceed with apparent rate constant (k app) of 0.107 and 0.122 min−1 in the presence of composite containing Ni and Cu nanoparticles, respectively. However, k app was increased with corresponding increase in temperature and its maximum value was found to be 0.815 min−1 at 88 °C with catalyst containing Ni nanoparticles. The formation of well dispersed Ni and Cu nanoparticles in the prepared hydrogel reflected that this hydrogel system can act as efficient stabilizing agent along with acting as a reactor medium. Recycling potential of catalysts was studied for five successive cycles.

Stimuli-responsive nanoparticle-nanofiber hybrids for drug delivery and photodynamic therapy

Hybrid nanomaterials possess integrated multi-components to syncretize various properties and functions within a single entity. Owing to this synergistic effect, they promise efficient anti-cancer therapy. In line with this target, we produced stimuli-responsive nanoparticle-nanofiber hybrids (NNHs) via embedding photoresponsive natural melanin nanoparticles (MNPs) within a biocompatible polycaprolactone (PCL) nanofiber matrix. Electrospinning was performed to produce monolithic and core-shell structured NNHs using a single and a coaxial nozzle. The NNHs were upgraded to drug delivery systems by model hydrophilic drug-ampicillin (amp)-loading. The drug release results showed that monolithic PCL meshes displayed a burst release, whereas nanohybrid formation with MNPs improved the release profile toward Fickian diffusion. Core-shell NNH presented a more sustained drug release profile than its MNP-free replica and monolithic NNH because its encapsulating shell layer hindered the diffusion of the drug. The photodynamic therapy accompanied by UV-A-irradiation on monolithic and core-shell NNHs yielded up to 34 % and 37 % malignant melanoma cell death. Moreover, this study proved the potency of MNPs-enhanced NNHs in drug delivery and photodynamic therapy applications. Even so, more efforts should be concerted to unlock unknown features of the NNHs, which have the power to advance emerging areas, including but not limited to material science, biosensing, and theranostics.

Developments on the Smart Hydrogel-Based Drug Delivery System for Oral Tumor Therapy

At present, an oral tumor is usually treated by surgery combined with preoperative or postoperative radiotherapies and chemotherapies. However, traditional chemotherapies frequently result in substantial toxic side effects, including bone marrow suppression, malfunction of the liver and kidneys, and neurotoxicity. As a new local drug delivery system, the smart drug delivery system based on hydrogel can control drug release in time and space, and effectively alleviate or avoid these problems. Environmentally responsive hydrogels for smart drug delivery could be triggered by temperature, photoelectricity, enzyme, and pH. An overview of the most recent research on smart hydrogels and their controlled-release drug delivery systems for the treatment of oral cancer is given in this review. It is anticipated that the local drug release method and environment-responsive benefits of smart hydrogels will offer a novel technique for the low-toxicity and highly effective treatment of oral malignancy.

Tannin coordinated nanozyme composite-based hybrid hydrogel eye drops for prophylactic treatment of multidrug-resistant Pseudomonas aeruginosa keratitis

Pseudomonas aeruginosa infection is a severe acute suppurative ulcer that engulfs virtually the entire tissue in a short period and leads to devastating destruction. Antibiotic therapy is a common approach for the prophylaxis and treatment of P. aeruginosa infection. However, it is often associated with serious side effects, complications, and multidrug resistance. Therefore, it has been a long-standing challenge to explore safe and effective methods for controlling P. aeruginosa infection. Herein, tannin-coordinated nanozyme composite-based hybrid hydrogels (TCNH) are developed and characterized for the prophylactic treatment of P. aeruginosa and multidrug-resistant P. aeruginosa infections using mouse keratitis as the animal model. The TCNH eye drops are constructed by photoinitiated free radical polymerization of acetylated gelatin solution containing self-synthesized tannin-coordinated Co₃O₄/Ag nanozyme composite. The as-prepared TCNH displays good dispersibility, peroxidase-like activity and in vitro/in vivo biocompatibility. The nanozyme composite in TCNH seems to penetrate the interior of bacteria and exhibited significant broad-spectrum antibacterial activity owing to its intrinsic and nanozymic catalytic properties. Furthermore, TCNH eye drops can be successfully applied to treat P. aeruginosa and multidrug-resistant P. aeruginosa keratitis. The findings of this study reveal the potential of tannin-coordinated nanozyme composite-based hybrid hydrogel eye drops for treating infectious diseases.

Nanotechnology: A Promising Approach for Cancer Diagnosis, Therapeutics and Theragnosis

Cancer remains the most devastating disease and the major cause of mortality worldwide. Although early diagnosis and treatment are the key approach in fighting against cancer, the available conventional diagnostic and therapeutic methods are not efficient. Besides, ineffective cancer cell selectivity and toxicity of traditional chemotherapy remain the most significant challenge. These limitations entail the need for the development of both safe and effective cancer diagnosis and treatment options. Due to its robust application, nanotechnology could be a promising method for in-vivo imaging and detection of cancer cells and cancer biomarkers. Nanotechnology could provide a quick, safe, cost-effective, and efficient method for cancer management. It also provides simultaneous diagnosis and treatment of cancer using nano-theragnostic particles that facilitate early detection and selective destruction of cancer cells. Updated and recent discussions are important for selecting the best cancer diagnosis, treatment, and management options, and new insights on designing effective protocols are utmost important. This review discusses the application of nanotechnology in cancer diagnosis, therapeutics, and theragnosis and provides future perspectives in the field.

Recent Advances in Nano-Formulations for Skin Wound Repair Applications

Skin injuries caused by accidents and acute or chronic diseases place a heavy burden on patients and health care systems. Current treatments mainly depend on preventing infection, debridement, and hemostasis and on supplementing growth factors, but patients will still have scar tissue proliferation or difficulty healing and other problems after treatment. Conventional treatment usually focuses on a single factor or process of wound repair and often ignores the influence of the wound pathological microenvironment on the final healing effect. Therefore, it is of substantial research value to develop multifunctional therapeutic methods that can actively regulate the wound microenvironment and reduce the oxidative stress level at the wound site to promote the repair of skin wounds. In recent years, various bioactive nanomaterials have shown great potential in tissue repair and regeneration due to their properties, including their unique surface interface effect, small size effect, enzyme activity and quantum effect. This review summarizes the mechanisms underlying skin wound repair and the defects in traditional treatment methods. We focus on analyzing the advantages of different types of nanomaterials and comment on their toxicity and side effects when used for skin wound repair.

Update of ultrasound-assembling fabrication and biomedical applications for heterogeneous polymer composites

As a power-driving approach, ultrasound irradiation is very appealing to the preparation or modification of new materials. In the review, we overviewed the latest development of ultrasound-mediated effects or reactions in polymer composites, and demonstrated its unique and powerful aspects on the polymerization or aggregation. The review generalized the different categories of heterogeneous polymer composites by defining the constituents, and described the shapes, sizes and basic properties of various purpose-specific or site-specific products. Importantly, the review paid more attention to the main biomedicine applications of heterogeneous polymer composites, such as drug or bioactive substance entrapment, delivery, release, imaging, and therapy, and emphasized many advantages of ultrasound-assembling approaches and heterogeneous polymer composites in biology and medicine fields. In addition, the review also indicated the prospective challenges of heterogeneous polymer composites both in ultrasound-assembling designs and in biomedical applications.

Gallium-Strontium Phosphate Conversion Coatings for Promoting Infection Prevention and Biocompatibility of Magnesium for Orthopedic Applications

Device-associated infections remain a clinical challenge. The common strategies to prevent bacterial infection are either toxic to healthy mammalian cells and tissue or involve high doses of antibiotics that can prompt long-term negative consequences. An antibiotic-free coating strategy to suppress bacterial growth is presented herein, which concurrently promotes bone cell growth and moderates the dissolution kinetics of resorbable magnesium (Mg) biomaterials. Pure Mg as a model biodegradable material was coated with gallium-doped strontium-phosphate through a chemical conversion process. Gallium was distributed in a gradual manner throughout the strontium-phosphate coating, with a compact structure and a gallium-rich surface. It was demonstrated that the coating protected the underlying Mg parts from significant degradation in minimal essential media at physiological conditions over 9 days. In terms of bacteria culture, the liberated gallium ions from the coatings upon Mg specimens, even though in minute quantities, inhibited the growth of Gram-positiveStaphylococcus aureus, Gram-negative Escherichia coli, andPseudomonas aeruginosa ─ key pathogens causing infection and early failure of the surgical implantations in orthopedics and trauma. More importantly, the gallium dopants displayed minimal interferences with the strontium-phosphate-based coating which boosted osteoblasts and undermined osteoclasts in in vitro co-cultures. This work provides a new strategy to prevent bacterial infection and control the degradation behavior of Mg-based orthopedic implants, while preserving osteogenic features of the devices.

Theoretical framework and experimental methodology to elucidate the supersaturation dynamics of nanocrystal growth

Supersaturation is the fundamental parameter driving crystal formation, yet its dynamics in the growth of colloidal nanocrystals (NCs) remain poorly understood. Here, we demonstrate an approach to characterize supersaturation during classical NC growth. We develop a framework that relates noninvasive measurements of the temporal, size-dependent optical properties of growing NCs to the supersaturation dynamics underlying their growth. Using this approach, we investigate the seed-mediated growth of colloidal Au nanocubes, identifying a triphasic sequence of supersaturation dynamics: rapid monomer consumption, sustained supersaturation, and then gradual monomer depletion. These NCs undergo different shape evolutions in different phases of the supersaturation dynamics. As shown with the Au nanocubes, elucidated supersaturation profiles enable the prediction of growth profiles of NCs. We then apply these insights to rationally modulate NC shape evolutions, decreasing the yield of impurity products. Our findings reveal that the supersaturation dynamics of NC growth can be more complex than previously understood. As our approach is applicable to many types of NCs undergoing classical growth, this work presents an initial step towards more deeply interpreting the phenomena governing nanoscale crystal growth and provides insight for the rational design of NCs.

A Facile and Universal Method for Preparing Polyethylene Glycol-Metal Hybrid Nanoparticles and Their Application in Tumor Theranostics

Metal ions are of widespread interest owing to their brilliant biomedical functions. However, a simple and universal nanoplatform designed for assembling a range of functional metal ions has not been explored. In this study, a concept of polyethylene glycol (PEG)-mediated transport of metal ions is proposed. 31 types of PEG-metal hybrid nanoparticles (P-MNPs) are successfully synthesized through anionic ring-opening polymerization (ROP), "thiol-ene" click reaction, and subsequent incorporation with multiple metal ions. Compared with other methods, the facile method proposed in this study can provide a feasible approach to design MNPs (mostly <200 nm) containing different metal ions and thus to explore their potential for cancer theranostics. As a proof-of-concept demonstration, four types P-MNPs, i.e., PEG-metal hybrid copper nanoparticles (PEG-Cu NPs), ruthenium nanoparticles (PEG-Ru NPs), and manganese nanoparticles (PEG-Mn NPs) or gadolinium nanoparticles (PEG-Gd NPs), are proven to be tailored for chemodynamic therapy, photothermal therapy, and magnetic resonance imaging of tumors, respectively. Overall, this study provides several metal ions-based nanomaterials with versatile functions for broad applications in cancer theranostics. Furthermore, it offers a promising tool that can be utilized for processing other metal-based nanoparticles and exploring their potential in the biomedical field.

Multifunctional GelMA platforms with nanomaterials for advanced tissue therapeutics

Polymeric hydrogels are fascinating platforms as 3D scaffolds for tissue repair and delivery systems of therapeutic molecules and cells. Among others, methacrylated gelatin (GelMA) has become a representative hydrogel formulation, finding various biomedical applications. Recent efforts on GelMA-based hydrogels have been devoted to combining them with bioactive and functional nanomaterials, aiming to provide enhanced physicochemical and biological properties to GelMA. The benefits of this approach are multiple: i) reinforcing mechanical properties, ii) modulating viscoelastic property to allow 3D printability of bio-inks, iii) rendering electrical/magnetic property to produce electro-/magneto-active hydrogels for the repair of specific tissues (e.g., muscle, nerve), iv) providing stimuli-responsiveness to actively deliver therapeutic molecules, and v) endowing therapeutic capacity in tissue repair process (e.g., antioxidant effects). The nanomaterial-combined GelMA systems have shown significantly enhanced and extraordinary behaviors in various tissues (bone, skin, cardiac, and nerve) that are rarely observable with GelMA. Here we systematically review these recent efforts in nanomaterials-combined GelMA hydrogels that are considered as next-generation multifunctional platforms for tissue therapeutics. The approaches used in GelMA can also apply to other existing polymeric hydrogel systems.

Monolith/Hydrogel composites as triamcinolone acetonide carriers for curing corneal neovascularization in mice by inhibiting the fibrinolytic system

Corneal neovascularization is a serious corneal pathological change caused by various factors. The drug delivery system is of great significance for the effective treatment of corneal neovascularization. Herein, we developed and characterized a monolith/hydrogel composite as the triamcinolone acetonide (TA) carrier for curing corneal neovascularization. The composite was prepared by photo-initiated free radical polymerization of multi-methacrylate substituted dodecamine organic molecular cage and post-modified by the sequential photo-initiated free radical polymerization of acrylated gelatin. The globular morphology and structural property of as-prepared composites were evaluated by scanning electron microscopy, Fourier-transform infrared spectroscopy and solid-state cross polarization magic angle spinning carbon-13 nuclear magnetic resonance. Then swelling ratio and the TA loading capacity were investigated then. Compared with gelatin hydrogel, the composites exhibited a decreased swelling ratio and an improved loading capacity. With good biocompatibility, the composite can sustainedly release TA for up to 28 days, and effectively inhibit corneal neovascularization with an alkali burn-induced corneal neovascularization model. Additionally, tandem mass tags-labeled quantitative proteomics were performed to identify differentially expressed proteins between vascularized and devascularized corneas. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the inhibition process could be primarily linked to the fibrinolytic system. These results demonstrated the potential of monolith/hydrogel composites as delivery systems in the therapy for biomedical diseases.

Hydrogel-based holographic sensors and biosensors: past, present, and future

Hydrogel-based holographic sensors consist of a holographic pattern in a responsive hydrogel that diffracts light at different wavelengths depending on the dimensions and refractive index changes in the material. The material composition of hydrogels can be designed to be specifically responsive to different stimuli, and thus the diffraction pattern can correlate with the amount of analyte. According to this general principle, different approaches have been implemented to achieve label-free optical sensors and biosensors, with advantages such as easy fabrication or naked-eye detection. A review on the different approaches, sensing materials, measurement principles, and detection setups, and future perspectives is offered.

MOF-based multi-stimuli-responsive supramolecular nanoplatform equipped with macrocycle nanovalves for plant growth regulation

Controllable and on-demand delivery of agrochemicals such as plant hormones is conducive to improving agrochemicals utilization, tackling water and environmental pollution, reducing soil acidification, and realizing the goals of precision agriculture. Herein, a smart plant hormone delivery system based on metal-organic frameworks (MOFs) and supramolecular nanovalves, namely gibberellin (GA)-loaded CLT6@PCN-Q, is constructed through supramolecular host-guest interaction to regulate the growth of dicotyledonous Chinese cabbage and monocotyledonous wheat. The porous nanoscale MOF (NMOF) with a uniform diameter of 97 nm modified by quaternary ammonium (Q) stalks is served as a cargo reservoir, followed by the decoration of carboxylated leaning tower[6]arene (CLT6) based nanovalves on NMOF surfaces through host-guest interactions to fabricate CLT6@PCN-Q with a diameter of ∼101 nm and a zeta potential value of -13.2 mV. Interestingly, the as-fabricated supramolecular nanoplatform exhibits efficient cargo loading and multi-stimuli-responsive release under various external stimuli including pH, temperature, and competitive agent spermine (SPM), which can realize the on-demand release of cargo. In addition, GA-loaded CLT6@PCN-Q is capable of effectively promoting the seeds germination of wheat and stem growth of dicotyledonous Chinese cabbage and monocotyledonous wheat (1.86 and 1.30 times of control groups, respectively). The smart supramolecular nanoplatform based on MOFs and supramolecular nanovalves paves a way for the controlled delivery of plant hormones and other agrochemicals for promoting plant growth, offering new insights and methods to realize precision agriculture. STATEMENT OF SIGNIFICANCE: To achieve controllable and sustainable release of cargos such as agrochemicals, a smart MOF-based multi-stimuli-responsive supramolecular nanoplatform equipped with supramolecular nanovalves was fabricated via the host-guest interaction between quaternary ammonium stalks-functionalized nanoMOFs and water-soluble leaning tower[6]arene. The as-prepared supramolecular nanoplatform with uniform diameter distribution demonstrated good cargo release in response to various external stimuli. The installation of synthetic macrocycles could effectively reduce cargo loss in the pre-treatment process. This type of supramolecular nanoplatform exhibited good promoting effect on seed germination and plant growth dicotyledonous Chinese cabbage and monocotyledonous wheat. As an eco-friendly, controlled, and efficient cargo delivery system, this supramolecular nanoplatform will be a promising candidate in precision agriculture and controlled drug release to attract the broad readership.

Rapid Magneto-Sonoporation of Adipose-Derived Cells

By permeabilizing the cell membrane with ultrasound and facilitating the uptake of iron oxide nanoparticles, the magneto-sonoporation (MSP) technique can be used to instantaneously label transplantable cells (like stem cells) to be visualized via magnetic resonance imaging in vivo. However, the effects of MSP on cells are still largely unexplored. Here, we applied MSP to the widely applicable adipose-derived stem cells (ASCs) for the first time and investigated its effects on the biology of those cells. Upon optimization, MSP allowed us to achieve a consistent nanoparticle uptake (in the range of 10 pg/cell) and a complete membrane resealing in few minutes. Surprisingly, this treatment altered the metabolic activity of cells and induced their differentiation towards an osteoblastic profile, as demonstrated by an increased expression of osteogenic genes and morphological changes. Histological evidence of osteogenic tissue development was collected also in 3D hydrogel constructs. These results point to a novel role of MSP in remote biophysical stimulation of cells with focus application in bone tissue repair.

Exploiting the role of nanoparticles for use in hydrogel-based bioprinting applications: concept, design, and recent advances

Three-dimensional (3D) bioprinting is an emerging tissue engineering approach that aims to develop cell or biomolecule-laden, complex polymeric scaffolds with high precision, using hydrogel-based "bioinks". Hydrogels are water-swollen, highly crosslinked polymer networks that are soft, quasi-solid, and can support and protect biological materials. However, traditional hydrogels have weak mechanical properties and cannot retain complex structures. They must be reinforced with physical and chemical manipulations to produce a mechanically resilient bioink. Over the past few years, we have witnessed an increased use of nanoparticles and biological moiety-functionalized nanoparticles to fabricate new bioinks. Nanoparticles of varied size, shape, and surface chemistries can provide a unique solution to this problem primarily because of three reasons: (a) nanoparticles can mechanically reinforce hydrogels through physical and chemical interactions. This can favorably influence the bioink's 3D printability and structural integrity by modulating its rheological, biomechanical, and biochemical properties, allowing greater flexibility to print a wide range of structures; (b) nanoparticles can introduce new bio-functionalities to the hydrogels, which is a key metric of a bioink's performance, influencing both cell-material and cell-cell interactions within the hydrogel; (c) nanoparticles can impart "smart" features to the bioink, making the tissue constructs responsive to external stimuli. Responsiveness of the hydrogel to magnetic field, electric field, pH changes, and near-infrared light can be made possible by the incorporation of nanoparticles. Additionally, bioink polymeric networks with nanoparticles can undergo advanced chemical crosslinking, allowing greater flexibility to print structures with varied biomechanical properties. Taken together, the unique properties of various nanoparticles can help bioprint intricate constructs, bringing the process one step closer to complex tissue structure and organ printing. In this review, we explore the design principles and multifunctional properties of various nanomaterials and nanocomposite hydrogels for potential, primarily extrusion-based bioprinting applications. We illustrate the significance of biocompatibility of the designed nanocomposite hydrogel-based bioink for clinical translation and discuss the different parameters that affect cell fate after cell-nanomaterial interaction. Finally, we critically assess the current challenges of nanoengineering bioinks and provide insight into the future directions of potential hydrogel bioinks in the rapidly evolving field of bioprinting.

Equilibrium swelling of multi-stimuli-responsive copolymer gels

Copolymer gels prepared by polymerization of thermo-responsive and anionic monomers demonstrate strong sensitivity to several triggers such as temperature, pH and ionic strength of aqueous solutions. For biomedical applications of these materials (as on-off switches in controlled drug delivery and release), fine tuning of their volume phase transition temperature (VPTT) and a sharp decay in degree of swelling upon transition from the swollen to the collapsed state are needed. These requirements are fulfilled under swelling of copolymer gels and microgels in water under acidic conditions, but are violated when tests are conducted under alkaline conditions or in aqueous solutions of salts with physiological salinity. A model is developed for equilibrium swelling of multi-stimuli-responsive copolymer gels in aqueous solutions with arbitrary pH and molar fractions of a monovalent salt. Unlike conventional approaches, the model accounts for secondary interactions between chains (hydrogen bonding) to describe the kinetics of aggregation of hydrophobic segments above VPTT. Material constants are determined by fitting experimental swelling diagrams on poly(N-isopropylacrylamide-co-sodium acrylate) gels with various molar fractions of ionic monomers. The effects of temperature, pH and molar fraction of salt on the equilibrium degree of swelling below and above VPTT are studied numerically.

Sustained Release Systems for Delivery of Therapeutic Peptide/Protein

Peptide/protein therapeutics have been significantly applied in the clinical treatment of various diseases such as cancer, diabetes, etc. owing to their high biocompatibility, specificity, and therapeutic efficacy. However, due to their immunogenicity, instability stemming from its complex tertiary and quaternary structure, vulnerability to enzyme degradation, and rapid renal clearance, the clinical application of protein/peptide therapeutics is significantly confined. Though nanotechnology has been demonstrated to prevent enzyme degradation of the protein therapeutics and thus enhance the half-life, issues such as initial burst release and uncontrollable release kinetics are still unsolved. Moreover, the traditional administration method results in poor patient compliance, limiting the clinical application of protein/peptide therapeutics. Exploiting the sustained-release formulations for more controllable delivery of protein/peptide therapeutics to decrease the frequency of injection and enhance patient compliance is thus greatly meaningful. In this review, we comprehensively summarize the substantial advancements of protein/peptide sustained-release systems in the past decades. In addition, the advantages and disadvantages of all these sustained-release systems in clinical application together with their future challenges are also discussed in this review.